Robert Duvall (seated) plays a farmer with a dark secret who wants his funeral held before he dies. He's aided by his assistant (Lucas Black, center) and an undertaker (Bill Murray).

Robert Duvall, that grand old man of the American cinema, has his juiciest role in years — one that will surely be remembered come awards time — as a crusty Tennessee hermit with a guilty secret in Aaron Schneider’s beautifully crafted “Get Low.”

This colorful folk tale is inspired by the true story of an eccentric who in 1938 threw a funeral party for himself while he was alive — an event that drew as many as 12,000 people.

For the filmmakers’ purposes, Duvall’s character, called Felix Bush, has spent 40 years alone on his farm — a self-imposed exile (“the first 38 years were the hardest”) for an offense that nobody but him really remembers at this point.

Did he kill a man? Kill two?

Even Bush’s old flame, Mattie (Sissy Spacek), a widow recently returned to town, isn’t really sure what happened, even though it may have involved her own late sister.

She’s certainly intrigued, along with everyone else, when Felix approaches Frank Quinn (Bill Murray), the local funeral director, to arrange a huge public party.

Frank thinks Felix is crazy, but he isn’t going to argue with Felix’s fat wad of cash when his seeming Depression-proof business is somehow failing.

Helping Felix with his plan — which includes his personal radio invitation to people in four counties to show up and tell stories about Felix and join in a raffle for his farm — is Frank’s young assistant, Buddy (Lucas Black), who is skeptical about the entire enterprise.

What Frank really wants — and needs — to do is to come clean before his impending end, something he just can’t bring himself to do. He, Frank and Buddy try mightily to recruit Felix’s only friend — an elderly black preacher (Bill Cobbs) who knows the whole story — as a surrogate.

It’s not exactly giving away anything to report that Felix’s eventual confession before the crowd is one of Duvall’s finest pieces of acting ever.

Duvall and Spacek are so in tune with each other’s rhythms — despite their 20-year age difference — that it’s hard to believe they’ve never acted together before.

And then there’s the dryly hilarious Murray as a man at the end of his rope — “What do you do when people won’t die?” — who will also likely be recognized at Oscar nomination time.

In “Get Low” — regional slang for being buried — these three pros take a story that could have been pure schmaltz and spin it into pure gold.